Process of plating metals.



coating, I may mention glue, water shellac, gum

UNITED STATES PATENT OFFICE.

MILTON W. FRANKLIN, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

PROCESS OF PLATING METALS.

No Drawing.

10 trolytica'lly coating non-conducting surfaces with metal The method formerly in use for coating non-conducting material, such as glass, with metal consists in first covering-the material to be coated with a varnish, such as copal or shellac. The varnish furnished a sticky surface which-was coatedwith graphite, and was then made the cathode in a plating bath. In the finished product the metal film is at tached to the glass, or other vitreous surface only by means of the varnish, which renders the articles thus plated unfit for use at high temperatures. Even at ordifia'ry room temperature the metal coating can be easily peeled ofi. i I

I have discovered that when the non-con ducting surface is coated with an adhesive which is permeable, and preferably also soluble, in the plating electrolyte, 'and a conducting layer is applied as usual, the plated film adheres very' firmly tothe surface upon which it is applied. To render the film of adhesive conducting, I prefer to use, in a.

finely divided state, the metal .to be plated, or a metal with which it will readily unite and incorporate the same, as by rubbing, into. the adhesive film. During'the plating process, metal is deposited on all sides of' each particle.

As a suitable material for the adhesive in arabic, annnar, or gum tragacanth- An aqueous, or other suitable solution of the gum is applied in a very thin layer upon the non-conducting surface to be coated. The surface is sprinkled with a very 'fine powder of metal, preferably of the metal to be plated,'for example, copper. is then'rubbed into the film of adhesiye. When the surface thus prepared is plated in the ordinary way, each grain of the original metal powder is coated with metal and the minute quantity of ad- Speciflcation of Letters Patent.-

Application filed August 4, 1911. Serial No. 642,267.

Patented Sept. 10, 1912.

hesive is practically dissolved out leaving a coating of pure metal. If any portion of the adhesive remains, it is probably incorporated with the metal.

The metal coating applied in this manner is very strong and can be removed from a smooth glass or other vitreous surface only with the greatest difiiculty. Its appearance, when viewed through the glass is similar to that of a mirror of the metal.

This process is particularly useful for coating vitreous or other non-conducting surfaces of condensers, ozone tubes and other electrical apparatus which are frequently operated at an elevated temperature.

WVhat I claim as new and desire to secure by Letters Patent of the United States, is,

l. The process of preparing non-conducting surfaces to receive an electrolytic deposit which consists in covering said surface with a film of adhesive material permeable with respect to the electrolyte in which the object is to be plated, incorporating conductive material into the adhesive film and electro-plating a metallic coating thereon.

2. The process of preparing a non-conductive surface to receive an electrolytic deposit which consists in covering said surface with a thin layer of adhesive material permeable and soluble in the solution which will subsequently form the plating .bath, working a conductive powder into said adhesive and electro-plating a metallic'coating thereon.

3. The process of preparing vitreous surfaces to receive an adherent electrolytic deposit of metal-which consists in applying a thin coating of water solublegum upon said surface, and incorporating into said coating MILTON W. FRANKLIN.

Witnesses:

BENJAMIN B. HULL, HELEN Onronn. 

